6 key considerations when choosing Category 6A cable

Stéphane Bourgeois from Belden looks at key factors to weigh up when opting for a Category 6A cable.

While all Category 6A products must meet the same base set of specifications, they are surprisingly different in their physical properties and how well they deliver at the extremes of performance. Those extremes are important because the extremes of today are the expectations of tomorrow.

1. Cable size and weight

Category 6A operates at frequencies up to 500 MHz, twice that of Category 6. Controlling noise and crosstalk at higher frequencies has meant Category 6A cables come in sizes up to 50% larger than their predecessors. Being larger means fewer cables can fit into a cable tray or conduit, which is a huge concern in retrofit installations. The newest category 6A cables on the market are only about 15% larger than Category 6.

2. Bend radius

With larger cable diameters also comes a larger bend radius, which is important when routing cables in tight spaces such as inside wall cavities. The bend radius also has an impact on the ability to route cables for maximum airflow within racks. The smaller the bend radius, the easier the cable is to route and install.

3. Installation complexity

Most Category 6A cables are larger because they have more twists in the copper pairs, larger splines separating the pairs and thicker outer jackets. All of these add up to cables that take longer to prepare and terminate. Thinner and more round cables take less time to install.

4. Power delivery

In a conventionally designed cable, the spline and jacket surrounding each copper pair create an insulated compartment that is prone to high heating when delivering Power-over-Ethernet. Newer thermal-barrier designs distribute heat around the circumference of the cable, eliminating hotpots, and some are capable of delivering up to 100 W PoE while keeping thermal rise within acceptable limits.

5. Channel length

Some small-diameter Category 6A cables may not support the full 100 m distance per channel, especially when delivering PoE, and need to be de-rated to less than full length. A cable that can handle the full 100 m not only provides an extra margin of performance, but supports a wider range of data centre configurations, including top-of-rack, end-of-row and middle-of-row configurations.

6. EMI shielding

There is a perception that shielded cable provides better noise immunity, but the effectiveness of the shield depends on the quality and reliability of the shield termination, balance of the twisted pairs and quality of the local and remote ground connections. The impedance of the ground connection can increase at higher frequencies, and differences in ground potential can couple noise into the conductors. Cable designs that effectively surround the conductors with a Faraday cage can provide an electromagnetic barrier without the potential drawbacks of grounding.

Category 6A 10GX System

Belden has introduced the Category 6A 10GX System to overcome the traditional drawbacks and compromises associated with Category 6A installation and use. The system has been designed to meet emerging application demands and support the needs of data centres, server farms, storage area networks, and campus backbones or network access nodes.

This article was originally published on The Right Signals Blog: www.belden.com/blog/datacenters/6-Key-Considerations-When-Choosing-Category-6A-Cable.cfm.

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